The present invention relates to an alternating current generator, and in particular, to an alternating current generator having two sets of connecting circuits for use in a vehicle.
Alternating current generators such as those disclosed in JP-A-4-26345 and JP-A-4-42759 are known.
JP-A-4-26345 discloses an alternating current generator having two sets of Y-form three-phase connecting circuits. The windings in a first set of two sets of Y-form three-phase connecting circuits are inserted in slots of a stator core and the windings in the second set of Y-form three-phase connecting circuits are inserted in slots of the stator core and are respectively arranged between the former slots so that the output vectors of the windings of the first set of Y-form three-phase connecting circuit have respective phase differences of 30 degrees with respect to the vectors of outputs of the windings of the second set of Y-form three-phase connecting circuits. The ripple of a combined output signal therefrom is decreased in this prior art device.
However, it is necessary to use a stator core provided with a great many slots, because two slots are necessary per phase and per pole.
As a result, the winding of the stator becomes complicated and the width of the core teeth of the stator core is halved, so that the core teeth are likely to deform during the winding process or the stator core assembling process.
In view of the above-described circumstances, the prior art disclosed in JP-A-4-42759 was devised to cope with the disadvantage of the prior art disclosed in the above mentioned JP-A-4-26345 by providing an alternating current generator including a first set of Y-form three-phase connecting circuit and a second set of delta-form three-phase connecting circuit. The windings of both of the Y-form and delta-form three-phase connecting circuits are inserted in the same slots so that the outputs vectors of the windings of the Y-form three-phase connecting circuit have respective phase differences of 30 degrees with respect to the vectors of outputs of the windings of the delta-form three-phase connecting circuit.
However, the prior art disclosed in JP-A-4-42759 has a disadvantage in that because one of the winding circuits is a delta-form three-phase connecting circuit, a circulating current flows through the delta-form three-phase connecting circuit, which generates undesirable heat.